Transportation systems

ABSTRACT

A transportation system including a network of tracks for remotely-controllable vehicles to run over, having intersections each enabling vehicles to be driven from one track to another track, and each comprising a junction track associated with vehicle detector means, signalling means and a computer for controlling vehicles on or approaching the junction track. A length of the junction track may be designated as queueing space sufficient to accommodate a predetermined maximum number of vehicles Q, and the computer may include means for maintaining a record of the number of vehicles q currently allocated to the queueing space, and a list of turn priorities for given destinations, and means for sending turning command signals to any vehicle whose destination gives it a turn priority greater than q, provided that q is less than Q.

United States Patent 1 Paddison l l July 22, 1975 TRANSPORTATION SYSTEMS3.748466 7/l973 Sihlcy et a] i, 246/187 B [75] Inventor: Denys IanPaddison, Godalming Primary Emmmer M Henson wood Jr.

England As'siiviunl Ex miinerReinhard J. Eisenzopf [73] Assignee:British Secretary of State for Allorm'). Agent or Firm-Elliott I.Pollock Defence, London England 22 Filed: Feb. 6, 1973 (57] ABSTRACT Atransportation system including a network of tracks [2|] Appl' 330l49for remotely-controllable vehicles to run over. having intersectionseach enabling vehicles to be driven from 30 Foreign Appncaiion priorityData one track to another track, and each comprising a Fch 10 1972United Kingdom H 6382/72 junction track associated with vehicle detectormeans.

signalling means and a computer for controlling vehi- [52] Us CL 104/88;246/63 R; 246/187 B cles on or approaching the junction track. A lengthof 51] Int. Ci. BblL 21/04 the rack may be dcsgnaled F [58] Field ofSearch H 104/88; 246/63 R '87 B space sufficient to accommodate apredetermined 246/187 C 632 maximum number of vehicles 0, and thecomputer may include means for maintaining a record of the [5b]Reierences Cited number of vedhiclles qfcurrentlv allocaed to thedqueuemg space, an a 1st 0 turn priorities or given estina- UNITED STATESPATENTS tions. and means for sending turning command signals 3334-3772/1966 'f l 346/63 C to any vehicle whose destination gives it a turnpriority 222 5; a] greater than q, provided that q is less than 0.1676mm) 7/1972 Jauquct 246/63 C [2 Claims, 8 Drawing Figures PI ["1 I II i i H i JE \a E LINESFROM TXl,

U2. ANPI P'ITO D5 5 r P3 O2 i COMPUTER F 402 I i: iii Hm w i'x'res iiiaa 2 J1 I a u ii an 4 r i I g l I i I g i i (1 I P7 E\ i a u:- d o d uh ,4 a J; J .i ;--"1 i 1 i i i l 1 52 T2 PATENTEDJuL22 ms 3.895584 SHEET4 COMPUTER TXP PATENTEDJUL22 ms 13.895; 584

SHEET 5 58 5| s 2 A I SERIAL TO B'STABLE RECEIVER"PARALLEL I I ICONVERTER ADDRESS DETECTOR CIRCUITS s 4 I INSTRUCTION DECODER CIRCUITSIII-,5 II

-s GUIDE WHEEL 53552 7 c L ACTUATORS APPARATUS 5 DATA TRANSMITTER FIG.5

PATENIEDJULZZ ms 3.895584 SHEET 7 ANY VEHICLES AT DETECTORS GEI' MESSAGE YES mom Di STORE IT i ITO 5 UPDATE LISTS OF VEHICLE 8 LOT ALLOCATIONSSIGNALS SENT VIA SI.S2 OR PROCESS MESSAGES (FIG. 7B)

ANY

MESSAGES STORED ENTER VEHICLE IN IS T2 LIST: SEND QUEUE HEADCORRESPONDIN SPECIFIC SLOT SLOT ON T2 ALLOCA ED FREE SIGNAL T0 SET ITSBISTABLE PUT q=q I A EXAMINE OUEUE SLOTS IN TI2 LIST;

||= SLOT (J) ALLOCATED,(J+I) FREE, J

SEND one sa T0 VEHICLE ALLOCATION TO (.1); UPDATE n2 LIST.

FIG. 7A.

TRAN SPORTATIUN SYSTEMS BACKGROUND OF THE INVENTION The presentinvention relates to transportation systems, and particularly totransportation systems in which comparatively small.remotely-controllable vehicles are driven over a network of tracks. Suchsystems have been proposed as an answer to problems of urban andsuburban transportation. offering the advantages of greater conveniencethan most conventional omnibus or train services, greater economy thanconven tional taxicabs. and a prospect of allowing a greater trafficcapacity in a given space than conventional road transport.

To achieve a high traffic flow rate, it is desirable that vehiclesshould be able to move in a regular stream (in which the individualvehicles move with substantially the same speed as each other, matchingtheir speed to the speed of the stream which is generally maintained atchosen speed) over at least a major part of each jour ney. To facilitatethis. various systems have been suggested in which vehicle controlsignals have been linked to and synchronized with periodic master timingsignals. Difficulties and complications arise, however. because manyessential operations in the system are in herently asynchronous. Forinstance. loading and unloading operations will require vehicles to betaken out of. and fitted back into the traffic stream. It is difficultto make arrangements for the merging of traffic streams consistent withany plan for the completely synchronous operation of all traffic streamsin a very busy system. The problems and difficulties involved are nottoo serious if the utilization factor (that is the number of vehiclesactually travelling on the track divided by the total number of trackspaces available) is low. However in urban situations. where there is agreat demand for transport facilities and space is at a premium. it isdesirable to attempt to satisfy the maximum demand with tracks occupyingthe minimum amount of space; it will therefore be advantageous tooperate the system as near as possible to its theoretical maximumcapacity. increasing the number of vehicles in use and reducing theamount of free track space not occupied by any vehicle. This greatlyincreases the difficulties of the merging and control processes.especially if it is desired to use the highest possible utilizationfactor while maintaining a good traffic flow rate and retaining a gooddegree of versatility in the choice of routes and stopping places tosuit individual requirements.

One suggested solution. which can be called the chess-playing orcomplete-schedule method. is to have a computer arranged to keep trackof the positions of all vehicles in the system and to tabulate theirpredicted positions at a series of times sufficient to complete alltheir journeys; before any vehicle is allowed to join or rejoin anytraffic stream, predictions of its proposed journey are compared withthe tabulation, and it is not allowed to start until all thesepredictions fit into unoccupied spaces in the tabulation. Thisarrangement has the disadvantage that the amount of computing requiredincreases approximately according to a power of the size of the system.and it is very inflexible.

Congestion at a popular destination could for in stance in thisarrangement prevent persons setting out on their way to it. instead ofallowing them the option of getting the nearest uncrowded station. orapproaching the destination by an alternative route. An even moreimportant disadvantage of any system attempting to achieve completelysynchronous. completely scheduled operation of all traffic streams witha high utilization factor is the disruption of the scheme which isliable to be caused by a fault in any vehicle or part of the controlsystem. While vehicles and control systems can be made highly reliable.it will be uneconomic if not impossible to ensure absolute reliability.and in any system of practically useful size some possibility ofbreakdowns should therefore be accepted and allowed for. In a complexsystem with many junctions and completely scheduled operation. anybreakdown is liable to have extensive repercussions; places which shouldbecome vacant do not become vacant. and places are reserved for vehiclesunable to come into them because of obstruction. The whole schedule hasto be re-planned and places reallocated taking into account the effectsof the fault. The amount of computation required for such reallocationrises as a power of the size of the system. and with a high utilizationfactor in a system of only moderate complexity it is likely to requirethe whole system to be brought to a standstill while a new schedule isworked out. The probability of such a standstill. with the accompanyingwaste and annoyance which it would cause, in effect places an economicor tolerance limit on the complexity and utilization factor of anysystem of completely synchronized traffic streams.

SUMMARY OF THE INVENTION These disadvantages can be avoided by a controlsystem which is convenient for both synchronous and asynchronousoperation. does not attempt complete scheduling or prediction of thewhole route of every journey. and accepts a possible need forasynchronous operations or queueing at any junction. This kind ofsystem. hereinafter called a Cabtrack system. allows more freedom inroute selection and modification; it can be arranged to direct vehiclesaround any obstruction or congested area.

It is an object of the present invention to provide a transportationsystem wherein remotely controllable vehicles can be controlled to formseparately synchronized traffic streams on different tracks. and to makecontrolled transfers from one stream to another at interseetions. bycontrol apparatus which can operate as a plurality of self-sufficient,comparatively simple decoupled parts, regardless of the complexity ofthe system as a whole.

According to the present invention, there is provided a transportationsystem comprising a plurality of tracks and a plurality of remotelycontrollable vehicles constructed to run over the said tracks. whereinthe said tracks comprise at least a first main track, a second maintrack and a junction track by which vehicles may be driven from thefirst main track to the second main track. and the system also comprisesfirst signalling means for sending control signals to vehicles on thefirst main track such that all vehicles on a continuous extended lengththereof receive the same control signals to cause the said vehicles toproceed in a first regular traffic stream along the said first maintrack. means for sending signals to selected ones of the said vehiclesto divert them on to the junction track, second signalling means forsending control signals to vehicles on the second main track such thatall vehicles on a continuous extended length thereof receive the samecontrol signals to cause the said vehicles to proceed in a secondregular traffic stream along the said second main track, thirdsignalling means for sending control signals to vehicles on the junctiontrack to control their progress on the junction track and to make themresponsive to signals derived from the second signalling means atselected times, further means for sending control signals derived fromthe second signalling means to vehicles on a part of the junction trackto cause the said vehicles to match their speed to the speed of the saidsecond regular traffic stream. a plurality of vehicle detector means fordetecting the passage of vehicles on the first main track. the secondmain track. and the junction track and receiving data signals from saidvehicles, and computer means connected to the vehicle detector means andto the first, second and third signalling means for controlling thetransfer of selected vehicles from the first main track to the secondmain track.

The first signalling means may include a first induc tive signallingcable incorporated in or mounted on the first main track, the secondsignalling means may include a second inductive signalling cableincorporated in or mounted on the second main track, and the thirdsignalling means may include a third inductive signalling cableincorporated in or mounted on the junction track. The said further meansmay include an extension of the second inductive signalling cableincorporated in or mounted on apart of the junction track. The furthermeans may also, or alternatively. include a connection for applyingcontrol signals of the second signalling means to the third signallingcable.

Preferably the system comprises a network of main tracks and a pluralityof intersections for connecting different pairs of the main tracks, eachof the intersections comprising a junction track associated withequipment comprising vehicle detector means, a third signalling meansand computer means for controlling vehicles on or approaching thejunction track. Preferably for control purposes the system isoperationally divided into parts, wherein each part includes oneintersection with associated equipment as hereinbefore specified, and iscapable of substantially self-sufficient operation without reference tothe computer means and vehicle detectors in other parts of the system;hence a standard form of computer means can be provided for each part.regardless of the size and complexity of the system as a whole.

In a typical part of such a system which includes a junction track bywhich vehicles may be driven from a first main track to a second maintrack, a length of the junction track may be designated as queueingspace sufficient to accomodate a predetermined maximum number ofvehicles 0, the vehicle detector means will include a first vehicledetector for ascertaining the des tination of each vehicle on the firstmain track as it approaches the junction where the junction trackdiverges from the first main track, and the computer means may includemeans for maintaining a record of the number q of vehicles currentlyallocated to the queueing space. maintaining a list of turn prioritiesfor given destinations, and allocating to each vehicle a turn priorityselected from the list according to the destina tion of the vehicle,comparing the allocated priority with the number q, and sending turningcommand signals to any vehicle which is allocated a turn prioritygreater than q. provided that q is less than Q. Alternatively oradditionally the computer means may be ar- 4 ranged to send signals toprevent any vehicle which is allocated a priority less than q fromturning on to the junction track.

The list of turn priorities for given destinations in each computermeans will generally be predetermined according to the relativepositions of the destinations concerned, relative to the intersectioncontrolled by the computer means. Thus a zero turn priority willgenerally be given for any destination which can be reached in minimumtime by continuing on the first main track past the intersection. A highturn priority will be given for any destination if turning at thecontrolled intersection will lead the vehicle on a significantly shorterroute to its destination than a turn at any subsequent intersection; thepriorities given will he in proportion to the saving in journey timeinvolved. However, the computer means may include provision formodifying the list of turn priorities in response to signals fromcomputers in other parts of the system, or from a central control. Forinstance, at an intersection where vehicles may turn left, some of theturn priorities may be temporarily increased in response to signalsindicating congestion at the next intersection allowing a left turn; andsignals indicating a temporarily obstructed line may be arranged toincrease most of the turning priorities by an amount related to thenumber of opportunities for avoiding the obstruction which exist in thenetwork between the obstruction and the intersection controlled.

In systems in which vehicles are moved independently over predeterminedtracks, it is common prac tice to divide the tracks notionally intosections which may be marked or identified in various ways, and todetermine or refer to the present locations of vehicles in the system byreference to the sections. In a novel control system which is preferredby the applicant, each vehicle is allocated to and associated with asection of track. hereinafter called a slot, in which it can come torest safely; each moving vehicle in such a system will therefore beallocated to a slot in advance of the vehicles actual position by anamount depending on the speed of the vehicle. The nature and advantagesof such a system are explained in co-pending patent application Ser. No.186,754, now US. Pat. No. 3,790,779, which is incorporated herein byreference.

EX EM PLARY DESCRIPTION Embodiments of the invention will now bedescribed, by way of example only, with reference to the accompanyingdrawings, of which:

FIG. I is a schematic diagram, or map, of an idealized transportationsystem,

FIG. 2 is a diagram of a transportation system de signed to suit anactual environment,

FIG. 3 is a schematic, larger scale diagram or map of a typicalintersection of a system as shown in FIG. 1 or FIG. 2,

FIG. 4 is a schematic, larger scale diagram or map of a typical loadingand unloading station,

FIG. 5 is a schematic circuit diagram of apparatus provided in eachvehicle,

FIG. 6 is a diagram of a model track used in experimental trials of thesystem and FIGS. 7A and 7B are flow charts illustrating the computerfunctions used to control the intersection of FIG. 3.

FIG. I shows an idealized network of one-way tracks. for vehiclesrunning in the direction of the arrows; the dots indicate stations wherevehicles may be loaded or unloaded, preferably in side-tracks which themain track by-passes as described hereinafter with reference to FIG. 4.Where two tracks cross at right angles. for instance at X in FIG. 1, itshould be understood that the tracks will be at different levels. andtraffic on either track will not interfere with traffic on the other.however at every crossing two one-way junction tracks (shown as arcs,for instance I) are provided. to enable vehicles to transfer from onetrack to the other The network shown comprises two loops elongated in anorth-south direction. crossing two loops which are elongated in aneast-west direction. with two junction tracks at each crossing. Clearlya network of this kind, where journeys may start and finish at anydesired stations, and any route consistent with the one-way restrictionsmay be followed, offers a versatile and effective transportation systemsuitable for urban transport, and may be extended as required byprolonging some of the loops or adding more loops. Clearly the networkcould be distorted to conform to topographical features andtransportation needs.

It may be noted that while the system of FIG. 1 is clearly only a simpleexample of the kind of system conceived as suitable and desirable forsatisfying urban transport demands. it is considerably more complex thanany systems known to have been operated with a high utilization factoron a completely-scheduled control scheme; it is thought that the numberof junctions involved even in this scheme would probably make acompletely-scheduled form of control become difficult or unsatisfactorywith a utilization factor of the order of 2571.

FIG. 2 shows schematically the main tracks of a hypothetical networkplanned, as part of an assessment study. to satisfy transportation needsin an actual city area; junction lanes would also of course be provided,as in FIG. 1 for instance, but they have been omitted from FIG. 2 forthe sake of simplicity. The squares on FIG. 2 represent loading andunloading stations of the kind shown in FIG. 4. FIG. 2 is presentedsolely as an illustration of the degree of complexity and versatilitywhich is contemplated and is considered to be made feasible by thepresent invention.

FIG. 3 shows a plan view of a typical intersection where a southboundtrack Tl crosses an eastbound track T2, including a junction track T12and associated equipment for allowing and controlling cars required togo from the track T] to the track T2. The broken lines on the tracksrepresent inductive signalling cables which are incorporated in. ormounted on. the structure of the tracks. A signalling cable 51 ismounted on the track T1 and is extended into the entrance end of thejunction track T12, up to a point P3 such that the rear of any vehiclereaching P3 will be clear of the track TI. The cable S1 is connected toreceive vehicle control signals from a transmitter TXI. Anothersignalling cable S2 is similarly mounted on the track T2 and is extendedsome way into the exit end of the junction track T12. up to a point P5.The cable S2 is connected to receive vehicle control signals from atransmitter TX2. A third signalling cable 512 is mounted on a length ofthe junction track T12 between the point P3- and the point P5. A part ofthis length between points P4 and P5 is designated as queueing space.The cable S12 is connected to receive vehicle control signals from atransmitter TXIZ.

Five vehicle detector units, D1 to D5 inclusive, are coupled to morelocalized inductive signalling loops, which are mounted in verticalplanes beside the tracks at various places. D1 is connected to a loopadjacent to the track Tl between points P1 and P2 upstream from theplace where the junction track T12 diverges from the track Tl; D2 isconnected to a loop adjacent to the track Tl2 near to the point P3; D3is connected to a loop adjacent to the track T12 downstream from thepoint P3", D4 is connected to a loop adjacent to the track T12 near thepoint P5, and D5 is connected to a loop adjacent to the track T2, at apoint P7 upsteam from the point P6 where the track T12 merges with thetrack T2. A computer C12 has input connections (not fully shown) fromthe transmitters TXI, TX2 and the vehicle detector units D1 to D5inclusive, and has output connections for sending control signals to thetransmitters TXl, TX2, TXI2 and the vehicle detector units DI to D5. Theoutgoing and returning conductors of the signalling cables S1, S2 andS12 are crossed over at regular intervals, so that receiving apparatusin each vehicle can check on the progress of the vehicle by do tectingand counting phase reversals which occur in the signals induced in thereceiving apparatus whenever the vehicle crosses a signal cablecrossover, according to a known technique in the art. It should beunderstood that FIG. 3 is schematic and not drawn to scale.

In operation of the system, vehicles will proceed southbound on thetrack TI and eastbound on the track T2. The vehicles on the track T]will normally proceed at a steady rate governed by the repetition rateof pulses applied to the cable 81 by the transmitter TXl, and thevehicles on the track T2 will normally proceed at a steady rate governedby the repetition rate of pulses applied to the cable 52 by thetransmitter TX2. The pulses from TXI may be quite independent of thepulses from TX2, and in general there need not be any kind ofsynchronization between the two pulse trains, although they may have thesame nominal repetition rate and for the sake of convenience they may bederived from a common source in some way which could give them apredetermined relative timing.

The vehicles which use the tracks of the system herein described willeach carry receiver apparatus for receiving signals from the signallingcables (for instance Sl, S2, S12) in the track on which it runs, andcontrol apparatus for controlling the speed of the vehicle in responseto these signals; details of suitable control apparatus are given in theaforesaid U.S. Patv No. 3,790,779. The control apparatus is arranged tocount slot-increment command pulses received via the signalling cables,to count pulses generated in the vehicle when it passes marker devicesin the track (including the crossovers of the signalling cableshereinbefore mentioned, but possibly also or alternatively includingmarker devices of some other type not shown) and to derive a signalcalled a position-lag signal which is adjusted according to thedifference between the results of the two counts. The control apparatusincludes a servo-system for controlling the speed of the vehicle, sothat the position-lag signal bears a predetermined relationship with thespeed of the vehicle and corresponds to the distance required todecelerate the vehicle to a stop safely and satisfactorily. In theplanning and operation of the transportation system as a whole, and inthe control of all the vehicles travelling over a typical intersectionof the kind shown in FIG. 3, each vehicle is notionally associated witha slot or part of the track in which it can safely be brought to rest ifthe signals from the signalling cables cease to be received; thus eachvehicle is associated with a slot which is in advance of the vehiclesactual position by a variable distance which depends on the vehicle'sspeed and is also therefore related to the current value of the vehiclesposition-lag signal.

Each vehicle also carries apparatus for communicating data concerningthe vehicle to any of the vehicle detectors such as D1 to D when itcomes within range of the detectors inductive signalling loop. Thus whena vehicle comes to the point P1. signals representing its destinationand the present value of the position-lag signal in its controlapparatus are sent to the detector D1 and thence to the computer C12.The signals may also indicate a serial number of the vehicle. and thetime of its arrival at P1 may also be sent to the computer C12.

The length of the track T12 between P4 and P5 is designated permissiblequeueing space and is sufficient to hold a predetermined number ofvehicles O. The computer C12 is arranged to maintain a record of atleast the total number q of vehicles currently associated with the slots(that is to say track lengths for one vehicle) which comprise thequeueing space, and also to maintain what is effectively a tabulation ofa set of GENERAL DESCRIPTION OF CONTROL ACTIONS AT AN INTERSECTION Whenthe computer C12 receives signals from the detector unit D1 indicatingthe arrival ofa vehicle at P1 and indicating the desired destination ofthe vehicle. it selects a corresponding turn priority from thetabulation. and compares it with the number (q) of vehicles currentlyassociated with the queueing space slots. If the selected turn priorityis greater than q, and q is less than Q. the computer sends a turningcommand signal to the vehicle. either through the transmitter TX] andcable S1 or through the detector unit D1. Signals representing theserial number of the vehicle may be sent as a part of the turningcommand signal to ensure that the turning command will be obeyed only bythe vehicle for which it is issued; alternatively if the signal is sentthrough the inductive loop connected to the detector D1 the serialnumber may be omitted if the loop is so short that there is no chance ofits signals being received by another vehicle. the computer actiontaking less time than the vehicle will take to pass the loop. If theselected turn priority is less than q, or if q Q indicating that thequeueing space is fully allocated to vehicles ahead of the vehicle nowbeing considered, the computer will send a go-straight on command signalto the vehicle to prevent it from turning on to the junction track T12.

The turning or prevention of turning is controlled by the placing ofguide wheels on the vehicle; each vehicle has two left-side guide wheelswhich can be engaged with the left-hand side of the track, and tworight-side guide wheels which can be engaged with the right-hand side ofthe track. mechanically interlocked so that they cannot engage bothsides of the track at once. A preferred construction for these guidewheels is described in a co-pending patent application Ser. No. 254,778which is incorporated herein by reference. In the case of theintersection shown in FIG. 3, where the junction track T12 diverges fromthe left-hand side (as seen looking forward from a vehicle goingsouthward on the track T1), the vehicle should engage its left-sideguide wheels with the left-hand side of the track in response to aturning command signal. and this will cause it to follow the left-handside onto the junction track T12. On the other hand, a go-straight-onsignal should cause engagement of the right-side guide-wheels and causethe vehicle to follow the right-hand side of the track T1 past theintersection. A vehicle which goes straight on will remain and continueunder the control of the pulses from the transmitter TX], at least untilit comes to another intersection where it may be directed to turntowards its destination.

When a vehicle has turned on to the junction track T12, it continues toreceive signals from the cable S1 until it is clear of the track T1;then the serial number of the vehicle and the present value of itsposition-lag signal is communicated via the detector unit D2 to thecomputer C12. These signals are used to confirm that the vehicle hasturned safely and is clear of the track T1; if they are not receivedwithin a predetermined time. the computer C12 may act to cause thesignals on the cable S1 to be interrupted. at least locally. in case thevehicle is blocking the junction. The signals from D2 are also used toconfirm, or correct if necessary. the computer's record of the slotassociated with the vehicle. At this point P3 or thereabouts the vehicleleaves the region controlled by the cable S] and comes onto the regioncontrolled by the cable S12.

The speed control signals used in the system may be of severalalternative types, namely specific signals, group signals, or generalsignals. The specific signals contain a code indicating the number ofthe vehicle for which they are intended. and only the vehicle con cernedwill respond to them. The general signals will. on the other hand. beacted upon by all vehicles which receive them; they may have a similarform to the specific signals but with a code representing all vehiclesinstead of a vehicle serial number. The group signals contain anothercode word, and will be acted upon by vehicles which have been maderesponsive to that code word. Thus a specific signal may be sent to aparticular vehicle to cause it to switch into a mode responsive to groupsignals containing a particular code word, either for a specified numberof signals. or until a further specific signal is caused to cancel thearrangement. Signals sent on the main track signalling cables such as S1and S2 will usually be general signals. whereas more we cific signalswill be required on the signalling cables in the junction tracks (S12for instance). Group signals may be used to reduce the number ofspecific signals which have to be sent.

The signals sent by the transmitter TX12 via the cable S12 will bevaried under the control of the computer C12 to govern queueing actionswhich may be required on the junction track between P3 and PS. The needfor queueing actions on the junction track and the amount of delayinvolved will clearly depend on the occurrences of gaps in the trafficflow on the track T2. This traffic flow is monitored by the detector D5,which sends to the computer CI2 an indication of the passage of eachvehicle together with an indication of the current value of itsposition-lag signal. which is related to its speed. From these signals.the computer C12 discovers when a gap will occur at the merging point;more precisely. its action is to deduce when a slot at a predeterminedpart of the track S2 between P7 and P6 is not allocated to any vehicle;then it sends a specific signal via TXIZ and $12 to any vehicleallocated to the slot at the head (exit end) of the queueing space, tomake that vehicle responsive to general command signals on the cable S2,at an appropriate time to ensure that if the vehicle responds normallyto the signals on the cable S2 it will match its speed to the speed ofthe vehicles on the track T2 and will arrive at the merger point in timeto fit in to the gap in the traffic stream which corresponds to theun-allocated slot. (This action is more fully described in the nextsection). The detector D4 is provided to check that the vehicle hasmatched its speed and its timing is correct, and to initiate appropriateemergency action to stop the vehicle, or turn it on to an escape route(not shown) if these conditions are not satisfied.

The computer C12 causes suitable signals to be sent through thetransmitter TXI2 and the cable S12 to cause each vehicle arriving on thejunction track to be allocated to the highest available (not alreadyallocated slot in the queueing space, and to add one to this allocationwhenever a vehicle is enabled to leave the head of the queue. Ifcontinuous traffic on the track T2 does not allow a safe exit for avehicle allocated to the head of the queue. that vehicle will come torest in a specified slot-length of the track just before P5. andsubsequent vehicles will come to rest in consecutive slot lengths behindit. On the other hand, if an opportunity for a safe merging into thetraffic on the track T2 arises before the vehicle allocated to the headof the queue has actually come to rest, it will be made responsive tosignals derived or relayed from the general command signals on the cableS2, and will proceed onto the track T2 without stopping on the junctiontrack T12.

It should be noted that the system herein described does not interferewith. or modify in any way, the progress of the main streams of vehiclesgoing straight on past the intersection on the main tracks T1 and T2;

such vehicles proceed at speeds determined entirely by the signals fromthe transmitters TXl and TX2 respectively, with no perturbations whichcould complicate the control required at subsequent intersections. Thesystem has the advantage of being very simple to under stand. simple toput into practice. and simple to analyze and yet it is very versatileand can be readily adapted to suit various situations. For instance itis not limited to any particular number queueing spaces. and the list ofturning priorities and the arrangements for modifying this list invarious circumstances can be altered as desired quite easily. One eachmain track, the traffic can be kept moving in a steady perfectlysynchronous stream with vehicles leaving it and joining it at intersections. and if desired (for instance to minimize conges tion in somearea) the speed of any such stream can be reduced by reducing therepetition rate of the signals sent by the corresponding transmitter (egTXl or TX2), without requiring any specific adjustment of any mergingoperations which may be already in progress when the change is made.

This arrangement, with queueing spaces on the junction tracks, also hasthe advantage that the control of a junction track will correspond tothe control of operations in the preferred form of station havingplatforms on by-passed tracks as hereinafter described, so that thecontrol apparatus for an intersection may be basically similar to thecontrol apparatus for a station. The development work on apparatus forintersection control will therefore assist the development of apparatusfor station control. and the similarity makes the system easier tounderstand and control.

DETAILED DESCRIPTION OF COMPUTER ACTIONS For a full description andappreciation of the simplicity and versatility of the system, it isdesirable to consider in greater detail the actions by which thecomputer C12 keeps account of the vehicles in the area under its controland the track slots allocated to them. These are surprisingly simple.The tracks under the control of the computer CI2 are notionally dividedinto slot lengths. which are given numbers for reference in thecalculations. One slot length, at the merger point P6 for instance. isgiven an arbitrary number, and consecutive slot lengths on the tracksleading up to this point are given consecutive numbers leading up tothis number. For instance a slot length beginning at P6 may bearbitrarily numbered 100. and if the length of junction track TI2 fromP2 to P6 comprises say 88 slot lengths, these slot-lengths from P2 to P6may be numbered consecutively from I2 to 99. Similarly if the track T2between P7 and P6 comprises say 52 slot lengths. they may be numberedconsecutively from 48 to 99. The queueing space between points P4 and P5on the track T12 will comprise several slot-lengths; to make theillustration definite, suppose that they are slots 49 to 54 inclusive.(Note that there will be some distinct but similarly-numbered slots onthe track T2, somewhere between P7 and P6.)

When a vehicle having a serial number v first comes within operatingrange of the inductive loop connected to the detector D5, it must be ata known position, say slot forty-eight on track T2, and the currentvalue of its position-lag signal will indicate how far ahead of itsactual position is the slot to which it is allocated. that is to say theslot in which it will come to rest if it receives no more controlsignals. The detector D5 will send to the computer signals indicatingthe serial number v and the current value of the position-lag signal 3;the computer will then in effect make a record of the number vassociated with the allocated slot number, in this case (48 g) since thedetector is at slot forty-eight. As the vehicle advances on the trackT2, its speed will be controlled so that its slot allocation increasesin accordance with a count of slot-incrementing signals which itreceives from the line $2; the computer C12 also receives these signals.and adds one to the allocated slot number stored in its record for eachvehicle which should respond to the signal.

Thus the computer CI2 in effect creates a tabulation of the serialnumbers and slot allocations of vehicles on the track T2. Each entry inthis tabulation is initiated by signals 1' and 48 g when the vehicleconcerned passes D5; thereafter the slot allocations are incrementedappropriately according to the signals on the cable S2. When a vehiclepasses the point P6, the entry relating to it may be discarded. Thesignals on the cable S2 will normally be general signals. to which everyvehicle on the track will respond in the same way. and clearly generalsignals should cause all the slot alloca tions in the tabulation to beequally incremented.

Similarly the computer also creates another tabula tion of the serialnumbers and slot allocations of vehicles on the track T12, in which eachentry may be initiated or confirmed by signals from the detector D2, andthe slot allocations are appropriately incremented in accordance withthe control signals transmitted to the vehicles either through thecables S1. S12, S2 or through the detector units and their inductivesignalling loops. The incrementing in this case will be slightly moreinvolved, as specific signals will be and group signals may be involved;cleariy a specific signal for a particular vehicle should only affectthe entry for that particular vehicle, and a group signal should onlyaffect the entries for vehicles which have been made responsive to thegroup code contained in the group signal. Specific signals which may beused to make particular vehicles responsive to, or non-responsive to. agiven group code should also operate logic circuits to make thecorresponding tabulation entries liable or not liable to incrementing bygroup signals including the given group code. (It should be noted thatthe system could be operated with specific signals and general signalsonly; the arrangements required for dealing with group signals should beregarded as an optional complication which may or may not be adopted inany particular embodiment or intersection in the system).

The tabulation relating to vehicles on the track T12 will clearly showhow many vehicles are allocated to slots between P3 and P5 or to slotsbetween P4 and P5; either of these numbers may be taken as the number qhereinbefore mentioned, depending on whether the track between P3 and P4is regarded as permissible queueing space or as space which should notnormally be used for queueing. The slot at the head of the queueingspace (at P5) will have a known number, say fiftyfour in this case. Whenthis slot is not already allocated to a vehicle. the computer shouldsend specific signals via the transmitter TX12 and the cable S12 to theleading vehicle on the track T12 (that is to the vehicle with thehighest slot allocation less than fiftyfour), to increase its slotallocation to fifty-four. The computer should then send specific signalsto the next vehicle to increase its slot allocation to fifty-three. andso on.

The length of track between P5 and the point P6 where the tracks T12 andT2 begin to merge together must be at least long enough to ensure that,ifa vehicle is initially at rest at the point P5 and is then enabled toreceive and respond to the general signals on the cable S2, it willreach a steady speed corresponding to the rate of these general signals(and therefore matching the speed of the traffic on track T2) before itreaches the merge point P6, indeed sufficiently in advance of the mergepoint P6 to enable this matching to be checked and to enable emergencystopping or diverting action to be taken before the merge point isreached if the matching is unsatisfactory. It follows that any vehiclewhich is made responsive to the general signals on the cable S2 when itis allocated to any slot up to P5 should in response to those signalsmatch the speed of the traffic on T2, and if its tabulated slotallocation is incremented according to the signals on S2, this tabulatedslot allocation should represent a slot ahead of its actual position byan amount corresponding to the rate of the signals on S2 and equal tothe position-lag distances of the vehicles already on the track T2.before it reaches the merge point P6. It follows that successful mergescan be arranged by making any vehicle allocated to slot fifty-four onthe track T12 responsive to the general signals on the line S2 when andonly when the corresponding slot fifty-four on the track T2 is notallocated to any vehicle. Hence the computer will be arranged so thatwhen the tabulation of vehicles on Tl2 contains an entry for slotfifty-four and the tabulation of vehicles on T2 does not contain anyentry for slot fifty-four, it will send a specific signal to the vehicleindicated in the entry for slot fifty-four of track T12, to make itresponsive to the general signals on the cable S2 (if it is not nearenough to S2 to receive these signals directly, but they can be relayedto it via TXl2 and T12 the preferred arrangement is describedhereinafter). At the same time, the computer should add an entry forthis vehicle to the tabulation of vehicles on T2, to mark the placeallocated to it in the traffic stream on T2. The next signal on $2increments the slot allocation of the vehicle, making slot fifty-four onthe track T12 available for the next following vehicle; the computerwill then send specific signals or a group signal to increase the slotallocations of the queued vehicles by one, thereby advancing the queue.

In the preferred arrangement for providing general signals, groupsignals and specific signals, and for controlling the responsiveness ofthe vehicles. every signal sent to a vehicle contains an address partand a function part. The address part may be either the serial number ofa specific vehicle, or one of two alternative group code words. Thereceiver apparatus in each vehicle contains decoder circuits fordetecting and responding to only those signals with appropriate addressparts. These circuits include a bistable circuit which can be set to aone state or reset to a zero state by given signals, and gate circuitsoperated by the bistable circuit, connected so that when the bistable isset the gate circuits will respond to and pass signals containing afirst one of the two group code words, and when the bistable is resetthe gate circuits will respond to and pass signals containing the secondgroup code word. All general signals on the cable S2 will contain thefirst group code word, and will therefore affect all vehicles whosedecoder bistable circuits are set. Any one of the following commands maybe represented by a corresponding instruction code word in the functionpart of a signal:

select right guide wheel select left guide wheel transmit data(Including vehicle serial number and its current position-lag) resetcontroller counters set decoder bistable reset decoder bistable countone slot increment command pulse The receiver apparatus is constructedto distinguish the instruction code words and initiate the appropriateresponse to each command.

As shown in FIG. 5 it includes a receiver 51 for detecting signalstransmitted by the inductive signalling cables and by any of the vehicledetector units and 13 local signalling loops within range. The signalsare converted from serial to parallel form by a conventional converter52 and are applied to address detector circuits 53 and instructiondecoder circuits 54. These are simple logic circuits. responsive tosignals representing prescribed codes or numbers.

Outputs of the address detector circuits are connected to inhibit orenable the instruction decoder circuits S4. Separate outputs from theinstruction decoder circuits control guide wheel actuators 55, a datatransmitter 56, the speed control apparatus 57. and the bistable circuit58. The speed control apparatus 57 provides the data transmitter 56 witha digital position-lag signal. and the bistable circuit 58 has outputsconnected to control two of the address detector circuits 53. A thirdaddress detector circuit is set to enable the instruction decodercircuits to respond to any specific signals including the prescribedserial number of the individual vehicle.

When a vehicle enters the junction track it is sent a signal to resetits bistable circuit. thereby inhibiting it from any response to thegeneral signals which are relayed from the cable S2 (or transmitter TX2)on to the cable S12. When it can safely be allowed to leave the queueingspace and proceed to the merge point P6. it is sent a signal to set itsbistable circuit once more. thus making it again responsive to thegeneral slotincrementing command signals.

If the detector D5 should detect the passage of a vehicle having aposition-lag signal substantially different from the value ofposition-lag which should correspond to the rate of the general signalson S2, it should act to inhibit any mergers on the track T2 and divertthe vehicle concerned to a maintenance area.

Clearly the actions required to control turns. queueing. and mergers. ashereinbefore described. have been shown to require only simple logicalprocedures. and the maintenance of the slot allocation lists requiresonly a list processing procedure. ofa kind known in the data processingart. so that it is unnecessary to describe them in any further detail. Asuitable program for performing the described actions in a satisfactorysequence is represented by the flow charts FIGS. 7A and 7B.

The reliability and safety of the system can clearly be increased byincorporating redundant components, providing a separate monitoringsystem. and other established techniques. The detectors D3 and D4 may beregarded as optional: if provided. they may be used as a part of amonitoring system. The signals need not be transmitted by inductivesignalling loops and cables as described; clearly any other convenientmeans for signalling to moving vehicles on predetermined tracks could beused. Leaking wave guides or transmission lines. conductor rails. oroptical signalling apparatus could be utilized. lnstead of forming atabulation of vehicle numbers and slot numbers. the computer could havea store in which one address is allocated for each slot in the length oftrack controlled; each vehicle num ber can then be entered at anappropriate address. and moved from one address to the next whenever theslot allocation of the vehicle is incremented.

PREFERRED FORM FOR STATIONS As hereinbefore mentioned. stations in thesystem are preferably provided on sidings which are by-passed by themain track. so that the main traffic stream may be unaffected by loadingand unloading operations. FIG. 4 shows a plan view of the arrangement ofa typical station and equipment associated with it. The station isserved by a track TP which leaves and rejoins the main track Tl. At apoint P10 the track TP divides into two parallel tracks serving separateplatforms P1 and P2; each of these tracks comprises a decelerationlength DN and an input queue space 10. The two parallel tracks mergeinto one at a point P1] beyond the platforms and continue forming anoutput queue space 00 between points P11 and P12 and an accelerationlength AN before rejoining the main track T1 at P13. A transmitter TXPis connected to signalling cables (not shown) mounted on the track TPbetween P10 and P12. Detector units D11 and D15 inclusive. thetransmitter TXP. the signalling cable S1 (not shown in FIGv 4, butmounted on the track Tl) and ticket transducers and other monitoringdevices (not shown) in stalled on the platforms P1 and P2 are allconnected to a computer CP which will monitor and control vehicles onthe track TP. The detector unit D11 is on the main track T1 upstreamfrom the divergence of the track TP; D12 is on track TP upstream fromP10; D13 and D14 are on the two platform tracks at the beginning oftheir deceleration lengths; and D15 is on the acceleration length AN.Clearly the operation of a station track may have many features incommon with the operation of a junction track. Signals from D11 are usedto form a tabulation of the vehicles passing on the main track; othersignals from D11 indicate any vehicles whose destination is the stationshown such vehicles should be sent a turning command signal unless theinput queueing spaces are fully allocated already. A tabula tion of thevehicles on the station track TP is derived from signals from thedetector D12. At P10. vehicles may be directed to whichever platformtrack has more unallocated slots at its platform and in its input queue.or may be directed to form batches for the two plat forms alternately.Specific signals are initiated and sent via the transmitter TXP toallocate vehicles to the highest available places in the input queue andat the platforms. When a vehicle has been allocated to the platform slotat which it is to stop. its allocation will not be increased until ithas come to rest at the allocated platform slot. time has been allowedfor unloading and reloading. and a positive indication has been receivedindicating that the vehicle is in a ready-to-go condition with all doorsclosed.

Vehicles may be loaded and given new destinations (for instance byinserting a ticket in a ticket transducer device) at the platform slot;alternatively control signals from a central control may be communicatedto empty vehicles. to cause them to leave for other stations where thedemand for vehicles is liable to exceed the number of vehiclesavailable. It is arranged that a vehicle departure from platform P1 willtemporarily inhibit any vehicle departure from platform P2 and viceversa. to prevent collisions at P11. Vehicles leaving the platforms aregiven signals sufficient to allocate them to the highest available slot(that is the slot nearest to P12) in the output queue. The mainsignalling cable of the main track T1 (not shown in FIG. 4) is extendedfrom P13 up the station track TP to the output queue region. and as inthe case of a junction track a vehicle allocated to the head of theoutput queue is transferred to the control of this signalling cable whena corresponding slot on the main track is not allocated. Like 1 thedetectors D3 and D4 in FIG. 3. the detectors D13. D14 and D15 may beregarded as optional. and if they are provided they may be used as partof a monitoring system.

EXPERIMENTAL TRIALS The operation of an intersection as hereinbeforedescribed with reference to FIG. 3. and the operation of a simplestation with only one platform track has been checked by running modelvehicles on a model track under the control of a Honeywell type 316computer. To save space and expense. the model track was formed as shownin FIG. 6. For the experiments relating to the operation of a stationthis was treated as a station like FIG. 4 but with only one platformtrack. with the tracks TI and TP curved to form an almost complete ovaland the track at P13 connected by a short length of track to the trackat D1]. For the experiments relating to the operation of anintersection, the model track was considered equivalent to anintersection like a mirror image of FIG. 3 with the south end ofTIconnected to the west end of T2 and the east end of T2 connected by ashort length of track to the north end of T1. Thus on the model theouter track is the main line. and the inner track is the platform trackin station experiments or the junction track in intersectionexperiments. The computer was controlled by the program given in theAppendix to this specification; this is written in the Honeywell DAPI6language. which is described in Honeywell Document No 130071629, M-l0l8DAP-lfi Manual" (December 1966 Persons skilled in the art will realisethat some of the instructions in this program relate to parameters ofthe model track such as the number of slots and the positions of thevehicle detectors. but clearly any real intersection or station could becontrolled similarly.

ACKNOWLEDGEMENT OF NEAREST KNOWN PRIOR ART The nearest prior art knownto the Applicant is contained in two papers Automated Network PersonalTransit Systems by H. Bernstein. and Development Simulation of an UrbanTransit System" by A. V. Munson Jnr. and T. E. Travis. of The AerospaceCorpora tion. El Segundo. Calif.

The paper by Bernstein suggests some of the advantages of atransportation system using remotelycontrolled vehicles on preparedguideways, each guideway being used by vehicles going in one directiononly,

with stations on siding lines. He states the desirability of runningtraffic at constant velocity on the main lines. and accelerating cars tothis velocity on local access lines before merging them into gaps in themain traffic stream. He also suggests the use of local intersectioncomputers to determine routing instructions for partic ular vehicles andto control manoeuvres required for traffic control according toinformation provided by wayside sensors located at the entry to thelocal computer's control zone. He suggests that routing instructionswould be based on tabular information stored t I 500- 577D (ill JMP JMPamp within the local computer for determining whether each car shouldturn or not, according to its destina tion. and that the routinginstructions might be modified by signals from a central computer. Thesearrangements are represented in FIG. 6 of the drawings accompanyingBernstein's paper. which may be compared with the Applicant's FIGS. 1and 3.

The paper by Munson and Travis describes a computer simulation of anintersection and traffic thereon in a system of the sort described byBernstein. This clearly shows that. though there are some similaritiesbetween their conception and the applicant's system, there are also somedifferences of fundamental impor tance.

In the system of these prior papers. all manoeuvering adjustments ofvehicle speeds required to allow traffic streams to merge safely areapplied to vehicles on a main-line, non-turning track. The traffic onjunction tracks apparently continues unchecked at a constant velocity,which must therefore be common to all the traffic streams in the system.

In this prior art system. the necessary manoeuvres are applied tovehicles in a main-line traffic stream; since this main-line trafficstream will comprise all vehicles bound for all subsequent intersectionsand destinations. one would expect it normally to comprise more vehiclesthan any typical sub-group of vehicles desiring to join or to leave themain track at a given intersection. The more congested a traffic streamis. the more difficult it is to apply manoeuvres to it withoutrepercussions and the more likely it is that it will be impossible toform a gap at a desired point in the stream with allowable manoeuveringdistance provided Munson and Travis results, in their FIG. 2. show thisto be a significant probability in practical conditions envisaged. It isnoted from the latter part of their section 2.4 that the reportedsimulation did not adequately allow for vehicles which would beprevented from joining the main stream by the impossibility of forming agap in the main line traffic to receive them immediately.

The applicants system is thought to be simpler and more satisfactorybecause the main-line traffic does not need to be adjusted to allowmergers. The necessary adjustments are made in the traffic on thejunction track. which will generally be less congested. By allow ingopportunities for queueing on the junction track. the applicants systemallows more opportunities for mergers to be used and makes diversionsless likely. It is more versatile since it does not require the speedsof traffic on the two intersecting main lines to be equal or to have anyother specific relationship.

The disclosures referred to do not in any way suggest or anticipate theapplicants arrangement of signalling means claimed hereinafter, theapplicant's arrangements for allocating vehicles to sections in whichthey may safely come to rest. the applicants arrangements for allowingqueueing on the junction tracks and comparing the tabulated turningpriorities with the number of vehicles already allocated to the queueingspace. or the applicant's use of group signals and receivers providedwith decoder units.

1 i I? Pinion/Mu isl l' ion lXlllrlFvllW m1 lirlAl 7U0 503 2600 JMP 600ISO 1 2700 JMP 700 400 505 3535 JMP 535 17 18 APPENDlX COMPUTER PROGRAMUSED FOR EXPERIMENTAL TRlALS-Cntinued 507 3100 JMP 100 1717 24000 1115 0510 41000 LL]. 0 1720 3706 JM? 1706 51 1 2100 JMP 100 1721 27733 IMA1733 512 3754 JMP 754 1722 15740 400 1740 514 3600 JMP 600 1724 737321.111: 1732 516 2724 MP 724 1726 27733 IMA 1733 517 3066 JMP 66 1727141206 ADA 521 3007 JMP 7 1731 3710 .1112 1710 522 3014 JMP 14 1732177776 0111* 1776 1 1 3 3 M 3 1733 264 DAG 264 524 3031 MP 31 1734 23420CA5 1420 527 2274 JMP 274 1737 12 04c 12 530 65 M 65 1740 260 DAC 260531 1 DAC 1 1741 0 111.7

532 2 DAC 2 1742 0 111.7

533 3 DAC 3 1743 0 111.7

534 4 DAC 4 1744 0 111.7

536 6 DAC 6 1746 0 111.7

537 7 DBL. 1747 0 111.7

545 177773 0111* 773 1 1 0 FLT 547 177771 01111 771 1 1 1 57 0 HLT 550100062 77716 17 0 HLT 551 177660 010* 660 1 1 7 0 HL-T 552 36 DAG 361762 0 HLT 553 74 DAC 74 6 0 L 556 0 111,7 1766 0 HLT 557 0 111,7 1767 OHLT 560 1700 D40 1700 1770 0 HLT 551 (1 111,7 1771 O HLT 5 2 g m- 1772 0BLT 571 44 DAC 44 574 A DAG a 2000 101000 1100 576 1700 1:140 1700 200:;50776 STA 577 1700 DAC 1700 I76 1 1 2004 24000 [RS 0 2005 3003 JMP 20032006 72545 1.011 545 2007 45076 1.04 2076 1 1 1700-1777 2010 120503JST=1 503 1700 2556 JMP 556 01 1 24000 IRS 0 1701 41 77 LGL 1 2012 30071m? 2007 1705 1 1733 STA 1733 016 10777 574 777 1705 140040 cm; 201710061 STA 61 1707 27733 IMA 1733 0 30020 OCP 20 1710 57740 SUB 1740 1 12021 4061 1.04 61 1712 3726 JMP 1726 2023 100400 SPL 1713 55740 ADD 17401 1 2024 3021 3 11 2021 1714 27733 IMA 1733 2025 5075 1.04 2075 1715 15710 ADD 17 10 2026 11.0503 JST-k 503 19 20 APPENDIX COMPUTER PROGRAM USEDFOR EXPERIMENTAL TRIALS-Continued 20 5077 L04 2077 2141 44717 LDA 717 a1 2030 12050 1 -JST* 503 2142 1000/ 5Z3 2031 L 53 2143 120500 J5T1= 50020.32 10764 STA 764 2144 4000 LDA O 2033 10770 STA 770 21115 41472 LGL 60 51 L 2146' 15232 ADD 2232 2035 10776 STA 776 2147 3211 JMP 221 1 20361400 0 C 2150 2310 JMP 310 2037 10061 STA 61 2151 33176 STX 2176 20403mm L1 11 2100 2152 11 177 STA 2177 2041 1 100 10 0111-1 2153 6560 ANA560 2042 10764 STA 764 21 4 10772 STA 772 2043 117535 L139 755 2155 5177L04 2177 2044 10776 STA 776 2155 1 0477 LGR 1 2045 5100 1,011 2100 21577174 ANA 2174 2046 0 H11? 2160 10773 STA 773 2047 0 HLT 2161 5177 L042177 2050 4536 1.04 536 2162 7173 ANA 2173 2051 120502 JSH 502 1 771 STA774 2052 101 100 S41 2164 5177 LDA 2177 2053 305 M 2350 2165 7172 ANA2172 2054 4531 LDA 531 1 404 1,93 12 2055 10770 STA 770 2 7 10775 STA775 2056 140040 C114 2170 13176 L071 2176 2057 725 17 L111: 5117 2171103150 3719* 2150 2060 50732 STA 732 J 1 172 3 00.3 11 0 2061 24000 11150 2173 m G 10 2062 3060 1MP 2060 2174 17 PAC 1'] 2063 10777 STA 777 2175Q HLT 2064 10061 574 61 2176 177775 D1 11* 2775 1 1 2065 3042 J71? 20422177 1 103 s 75 2066 177602 0111* 2602 1 1 (1)2200-22770 2067 7174 AG764 2200 453 1, 53 2070 1 11601 STA* 2601 2201 120502 JST=1= 502 2071 111706 STA-k 2706 2202 72543 L072 543 2072 1 11606 5TA* 2606 2203 100100SLZ 2073 1 11603 574* 2603 2204 361 1 JMP 2611 2074 1 1 1605 5171* 26052205 40477 1.611 1 2075 1 1 1611 5711* 261 1 2206 24000 IRS 0 2076 0 ML?2207 3203 JW? 2203 2077 1 11612 5771* 61 2 2210 3223 JMP 2223 221 1 11212 STA 2212 I 12100-21771) 2212 30230 0GP 230 2100 101000 NOP 22135233 LDA 2233 2101 4776 L114 776 2214 120503 dST* 503 2102 101400 SW12215 4761 LDA 761 2103 3050 1MP 2050 2216 120502 .JST* 502 2104 300200GP 20 2217 120517 JST* 517 2105 0 2020 5:;1 2220 72761 LDX 761 2106 311 1 JM? '?1 1 f1 2221 S0717 STA 717 a 1 21117 1552 LDA 552 2222 3200 0M?2200 21 1O 31 12 JMP 21 12 2223 72540 LDX 540 21 1 1 4553 LDA 553 2224101 SLN 21 12 10760 STA 760 2225 32766 STX 766 21 13 4061 LDA 61 222640477 1.138 1 2114 16760 SUB 760 2227 101 100 SLN 2115 100400 SPL. 223032765 STX 765 2116 3200 JMP 2200 2231 3300 J14? 2300 21 17 10061 STA 612232 30130 00? 2120 16760 SUB 760 2233 131604 INA 1604 2121 101400 SM!2234 4531 LDA 531 2122 31 17 J14? 21 17 2235 10763 STA 763 2123 4777 LDA777 2236 72762 LDX 762 2124 141206 ASA 2237 44577 LDA 577 1 1 2125 10777STA 777 2240 100100 51.2 2126 141206 ASA 2241 120500 JS'H 500 2127 10770STA 770 2242 141206 ASA 2130 101004 SST 2243 101400 5111 2131 3200 JMP2200 2244 120500 dST* 500 2132 120514 JST* 514 2245 140100 55? 213321620 JST 2620 2246 50642 STA 642 1 1 2134 3200 JMP 2200 2247 140040 CRA2135 4000 LDA 0 2250 50577 STA 577 1 2136 140407 TCA 2251 3355 J-"IP2355 2137 10761 STA 761 2252 72762 LDX 762 2140 10000 STA O 2253 44577LDA 577 1. 1

21 22 APPENDIX COMPUTER PROGRAM USED FOR EXPERIMENTAL TRIALS-Continued225 100400 SPL 2365 5375 LDA 2375 2255 120500 'JS'H 500 2366 101000 N0?2256 3355 1M? 2355 2367 16762 SUB 762 2257 155 1 LDA S54 2370 101 100SMI 2260 10755 STA 755 2371 120500 JST* S00 2261 305'.) JWP 2050 2372323 4 JMP 2234 2262 1 10003 STA* 3 2373 0 HLT 2263 1 10002 S'I'A'k 22374 20 DAG 20 226 1 0 HL/f 2375 40 DAG 10 21165 5263 LDA 2263 2376 0HLT 2266 14772 A01. 772 2377 0 HLT 2267 120503 .151 S03 2270 1767 LDA767 2271 1l1206 AOA 2273 3355 MP 2355 2400 2052 MP 52 2274 5262 1.042262 2401 100004 SR1 2275 14772 400 772 2402 3414 JMP 2414 2276 120503057* 503 2403 30030 001 30 2277 3355 JMP 2355 2404 141206 404 2300 725431.0): 543 2410 30730 002 730 2301 44723 1.04 723 ,1 241 1 131030 11141030 2302 100040 SZE 2412 3411 .mP 2411 2303 3307 JMP 2307 2413 1034003110* 2400 2304 24000 1115 0 2414 16536 5115 536 2305 3301 JMP 2301 2415101040 5112 2306 102507 JMP=I= 507 2416 3500 JMP 2500 2307 120501 357*501 2417 14536 400 536 2310 140040 034 2420 15430 400 2430 2311 50723574 723 1 2421 11433 574 2433 2312 4000 1.04 0 2422 72544 1.011 544 231314534 400 534 2423 45435 1.04 2435 1 2314 10771 574 771 2424 1205231157* 523 2315 101000 NOP 2425 24000 IRS 0 2316 101000 N0? 2426 3423 JM?2423 2317 4775 1.04 775 2427 3440 JMP 2440 2320 101000 NO? 2430 130260INA 260 2321 100040 520 2431 106612 4114* 612 2322 120505 057* 505 2432151330 574* 2330 1 2323 44574 1.04 574 1 1 2433 130262 104 262 232416773 $00 773 2434 120306 057* 306 2325 22540 045 540 2435 120316 JST*316 2326 23347 045 2347 2436 120322 JST* 322 2327 120500 357* 500 2437120305 357* 305 2330 120500 357* 500 2440 4532 1.04 532 2331 10762 574762 2441 120504 357* 504 2332 10000 574 0 2442 15476 400 2476 2333 445771.04 577 1 2 3 41474 LGL 4 2334 6560 4114 560 2444 10000 STA 0 233516772 500 772 2445 5435 1.04 2435 2336 101040 SNZ 2446 120523 057* 5232337 3350 JMP 2350 244'! 4532 LDA 532 2340 4764 1,134 7 1 2 150 120504J51* 50 1 2341 101040 5103 2451 1 1000 ADD 0 2342 3750 JMP 2750 5 4147'!LGL 1 2343 4772 1.04 772 5 10000 STA 0 2344 15374 ADD 2374 2 15 1 5436LDA 2 136 231 5 50577 STA 577 ,1 2455 120523 JST* 523 2346 3355 J74?2355 2456 4531 LDA 53! 2347 3 D45 3 2 157 120504 JST=1= 504 2350 47711.04 771 2460 14000 ADD 0 2351 22532 045 532 2461 41474 MEL 4 2352 3360JMP 2360 2462 10000 STA 0 2353 102512 0111 512 2463 5437 1.04 2437 23543252 JMP 2252 2464 120523 JST* 523 2355 100002 5110 2465 4532 1.04 5322356 120515 357* 515 2466 120504 1157* 504 2357 3100 JMP 2100 2467 14000400 0 2360 4573 1.04 573 2470 41477 1.01. 1 2361 101000 NOP 2471 141206404 2362 16762 SUB 762 2472 3510 JMP 2510 2363 100400 SPL 2473 0 111.7

236 1 120500 JST* 500 2474 0 BLT

1. A transportation system comprising a plurality of tracks and aplurality of remotely controllable vehicles constructed to run over thesaid tracks, wherein the said tracks comprise at least a first maintrack, a second main track, and a junction track by which vehicles maybe driven from the first main track to the second main track, and thesystem also comprises first signalling means for sending control signalsto vehicles on the first main track such that all vehicles on acontinuous extended length thereof receive the same control signals tocause the said vehicles to proceed in a first regular traffic streamalong the said first main track, means for sending signals to selectedones of the said vehicles to divert them on to the junction track,second signalling means for sending control signals to vehicles on thesecond main track such that all vehicles on a continuous extended lengththereof receive the same control signals to cause the said vehicles toproceed in a second regular traffic stream along the said second maintrack, third signalling means for sending control signals to vehicles onthe junction track to control their progress on the junction track andto make them responsive to signals derived from the second signallingmeans at selected times, further means for sending control signalsderived from the second signalling means to vehicles on a part of thejunction track to cause the said vehicles to match their speed to thespeed of the said second regular traffic stream, a plurality of vehicledetector means for detecting the passage of vehicles on the first maintrack, the second main track, and the junction track and receiving datasignals from the said vehicles, and computer means connected to thevehicle detector means and to the first, second and third signallingmeans for controlling the transfer of selected vehicles from the firstmain track to the second main track.
 2. A transportation system asclaimed in claim 1 and wherein the first signalling means comprises afirst inductive signalling cable incorporated in or mounted on the firstmain track, the second signalling means comprises a second inductivesignalling cable incorporated in or mounted on the second main track,the third signalling means comprises a third inductive signalling cableincorporated in or mounted on the junction track, and the said furthermeans comprises an extension of the second inductive signalling cableincorporated in or mounted on a part of the junction track.
 3. Atransportation system as claimed in claim 1 and wherein thE firstsignalling means comprises a first inductive signalling cableincorporated in or mounted on the first main track, the secondsignalling means comprises a second inductive signalling cableincorporated in or mounted on the second main track, the thirdsignalling means comprises a third inductive signalling cableincorporated in or mounted on the junction track, and the said furthermeans comprises a connection for applying control signals of the secondsignalling means to the third signalling cable.
 4. A transportationsystem as claimed in claim 1 wherein the said control signals sent tothe vehicles have address parts and instruction parts, and in eachvehicle there is provided a receiver incorporating decoder means fordistinguishing prescribed address parts and instruction parts, andvehicle control apparatus responsive to output signals from the decodermeans for initiating a prescribed response to predetermined controlsignals.
 5. A transportation system as claimed in claim 4 wherein thedecoder means in each vehicle comprises a bistable circuit, means forsetting the bistable circuit in response to a control signal comprisinga prescribed specific address part specific to the individual vehicleand a first prescribed instruction part, means for resetting thebistable circuit in response to a control signal comprising the saidspecific address part and a second prescribed instruction part, andinstruction detector means controlled by the bistable circuit responsiveto the instruction part of any control signal whose address part is afirst prescribed group address whenever the bistable circuit is set, andresponsive to the instruction part of any control signal whose addresspart is a second prescribed group address whenever the bistable circuitis reset.
 6. A transportation system comprising a network of main tracksand main track signaling means for signaling to vehicles on each maintrack so that all vehicles on a continuous extended length of any maintrack will receive the same control signals for causing said vehicles toproceed in regular traffic streams along said main track; the networkhaving a plurality of intersections which each comprise a one-wayjunction track connecting two of the said main tracks and havingintersection control means provided for each intersection capable ofsubstantially self-sufficient operation for controlling vehiclesapproaching the junction track and on the junction track thereof; thejunction track leading from a first main track to a second main track ateach of said intersections, the first main track being equipped withfirst main track signaling means, the second main track being equippedwith second main track signaling means, and the intersection controlmeans comprising means for directing selected vehicles from the firsttrack onto the junction track, third signaling means for sending controlsignals to vehicles on the junction track to control their progress andto make selected vehicles responsive to signals derived from the secondmain track signaling means at selected times, further means for sendingcontrol signals derived from the second main track signaling means tovehicles on a part of the junction track, a plurality of vehicledetector means for detecting the passage of vehicles on the first maintrack, the second main track, and the junction track and for receivingdata signals from the said vehicles, and computer means connected to thevehicle detector means and to the first, second and third signalingmeans for controlling the transfer of vehicles from the first main trackover the junction track to the second main track.
 7. A transportationsystem as claimed in claim 6 wherein each vehicle is notionallyallocated to a section of the track in which it may safely come to rest,and in each of the intersections a length of the junction track isdesignated as queueing space sufficient to accomodate a predeterminedmaximum number of vehicles Q and the intersection control meanscomprises: A first vehicle detector means for ascertaining thedestination of each vehicle and an indication of the section of track towhich it is currently allocated as it approaches the entry to thejunction track, and computer means for maintaining a list of turnpriorities for given destinations, allocating to each vehicle a turnpriority selected from the list according to the destination of thevehicle, maintaining a record of the number q of vehicles currentlyallocated to the queueing space, comparing the allocated turn prioritywith the number q, and sending turning command signals to any vehiclewhich is allocated a turn priority greater than q if and only if q isless than Q, so as to direct the vehicle on to the junction track.
 8. Atransportation system as claimed in claim 7 wherein the first vehicledetector means comprises means for receiving a position-lag signal fromeach passing vehicle, which represents the distance between the actualposition of the vehicle and the track section to which it is currentlyallocated, and the computer means comprises means for determining thetrack section to which the vehicle is currently allocated by adding thevehicle''s position-lag signal to a signal representing the position ofthe vehicle when detected by the first vehicle detector means.
 9. Atransportation system as claimed in claim 8 wherein the computer meanscomprises means for maintaining a list of all vehicles currentlyallocated to sections of the junction track and the sections to whichthey are allocated, and a list of all vehicles currently allocated toneighbouring sections of the second main track and the sections to whichthey are allocated, and means responsive to the control signals sentthrough the said second and third signalling means to the said vehiclesfor incrementing the sections indicated in the said lists for thevehicles which should respond to the said control signals.
 10. Atransportation system as claimed in claim 9, wherein each main track hasa signalling means for sending control signals to vehicles thereon tocause the said vehicles to proceed in a regular traffic stream along themain track, and each vehicle is notionally allocated to a section of thetrack in which it may safely come to rest, and the system also comprisesa plurality of stations each having: at least one platform trackconnected at both ends to a main track of the system, first vehicledetector means for detecting each vehicle on the main track as itapproaches the entrance end of the platform track, ascertaining whetherit is desired to stop at the station and receiving an indication of thetrack section to which it is currently allocated, means for sending aturning command signal to any vehicle which is desired to stop at thestation to cause it to turn on to the platform track provided that theplatform track is not unduly congested, means for maintaining a list ofvehicles continuing on the main track and a list of vehicles on theplatform track, indicating the track sections to which the vehicles areallocated, and means for rendering any vehicle desired to leave thestation responsive to the signalling means of the main track at aninstant when a predetermined section on the part of the main trackbetween the two ends of the platform track is not allocated to anyvehicle.
 11. A transportation system as claimed in claim 8 wherein thecomputer means comprises means for maintaining a list of track sectionson the junction track and track sections on the second main trackindicating all vehicles currently allocated to the said track sections,and means for transferring vehicle indications in the said list inresponse to control signals sent through the said second and thirdsignalling means to cause the vehicles to advance.
 12. A transportationsystem as claimed in claim 8 wherein the computer means comprises meansfor sending a control signal to any vehicle allocated to a prescribedtrack section at tHe head of the queueing space to render to saidvehicle responsive to signals derived from the second signalling meansat an instant when a predetermined section of the second main track hasno vehicle allocated to it.